In a known wobble plate type compressor, the rotation of the drive shaft is converted into reciprocating motion by a cam rotor having a sloping end surface that is mounted on a drive shaft and a wobble plate disposed on the sloping end surface with a needle-type thrust bearing therebetween. The wobble plate is restrained against rotation so that upon rotation of the cam rotor, it is caused to wobble.
U.S. Pat. No. 4,073,603 discloses one type of rotation restraining means for a wobble plate of a compressor, that is, a ball member that is mounted on a pin that extends radially outwardly from the wobble plate and is trapped between a pair of opposed track members near the lower portion of compressor housing. In this arrangement, the rotation restraining force acts against the ball and is transferred to the wobble plate through a pin on which the ball is affixed. Because the pin is small relative to the forces involved, the durability of the pin and ball element has suffered. Simply using a larger pin is not suitable because it requires a larger seat in the wobble plate which in turn affects the durability of the wobble plate.
In the U.S. Pat. No. 4,105,370, there is disclosed a modification of the above mentioned rotation restraining means in which the ball element is disposed between and adapted to slide relative to the opposed concave faces of a generally cylindrical guide. In this arrangement, there is line contact between the ball element and the cylindrical guide which causes uneven wear between the ball element and the guide.
Another type of rotation restraining means is shown in FIGS. 1-4 which includes bearing element 1 having a slot 11 at one end that is disposed in a radial bore in the wobble plate 2. A plate 3 mounted in the bottom portion of the crank chamber of the compressor housing is seated in the slot 11 of the bearing element 1 to restrain the wobble plate 2 from rotation.
In this arrangement, the contact between the bearing element 1 and the plate 3 is generally a face contact. However, line contact between the bearing element 1 and plate 3 may occur due to variations in assembly and to stress during operation of the compressor. Abnormal wear and abrasion results when the rotation restraining torque is applied eccentrically against the contact area between the bearing element 1 and the plate 3, thereby causing premature failure.
One resolution of the above mentioned disadvantages is disclosed in U.S. Pat. No. 4,297,085. The guide rod is replaced by the guide plate and the ball element is disposed in a slot in the wobble plate. However, this rotation restraining means has a relatively large number of parts and is relatively complicated in assembly.